Previously known welding apparatus have been adapted to sense weld quality. U.S. Pat. Nos. 4,542,277, 4,684,778 and 4,861,959 to Dimitrios G. Cecil disclose a welding apparatus in which linear displacement of the electrodes provides position or condition signals for transfer to indicator devices. However, such apparatus have limited utility to the extent that they do not identify particular conditions before welding operation takes place. In addition, the known apparatus require constant monitoring by a user in order to ascertain the results of each welding step.